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Restructure autovacuum in two processes: a dummy process, which runs

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continuously, and requests vacuum runs of "autovacuum workers" to postmaster.
The workers do the actual vacuum work.  This allows for future improvements,
like allowing multiple autovacuum jobs running in parallel.

For now, the code keeps the original behavior of having a single autovac
process at any time by sleeping until the previous worker has finished.
This commit is contained in:
Alvaro Herrera
2007-02-15 23:23:23 +00:00
parent eecbb33267
commit 1820650934
16 changed files with 807 additions and 250 deletions
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190
src/backend/postmaster/postmaster.c
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@ -37,7 +37,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.521 2007/02/13 19:18:54 tgl Exp $
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.522 2007/02/15 23:23:23 alvherre Exp $
*
* NOTES
*
@ -129,13 +129,14 @@
* authorization phase). This is used mainly to keep track of how many
* children we have and send them appropriate signals when necessary.
*
* "Special" children such as the startup and bgwriter tasks are not in
* this list.
* "Special" children such as the startup, bgwriter and autovacuum launcher
* tasks are not in this list. Autovacuum worker processes are on it.
*/
typedef struct bkend
{
pid_t pid; /* process id of backend */
long cancel_key; /* cancel key for cancels for this backend */
bool is_autovacuum; /* is it an autovacuum process */
} Backend;
static Dllist *BackendList;
@ -217,7 +218,8 @@ static bool FatalError = false; /* T if recovering from backend crash */
bool ClientAuthInProgress = false; /* T during new-client
* authentication */
static bool force_autovac = false; /* received START_AUTOVAC signal */
/* received START_AUTOVAC_LAUNCHER signal */
static bool start_autovac_launcher = false;
/*
* State for assigning random salts and cancel keys.
@ -270,9 +272,11 @@ static long PostmasterRandom(void);
static void RandomSalt(char *cryptSalt, char *md5Salt);
static void signal_child(pid_t pid, int signal);
static void SignalChildren(int signal);
static void SignalSomeChildren(int signal, bool only_autovac);
static int CountChildren(void);
static bool CreateOptsFile(int argc, char *argv[], char *fullprogname);
static pid_t StartChildProcess(int xlop);
static void StartAutovacuumWorker(void);
#ifdef EXEC_BACKEND
@ -1145,13 +1149,12 @@ ServerLoop(void)
/*
* Wait for something to happen.
*
* We wait at most one minute, or the minimum autovacuum delay, to
* ensure that the other background tasks handled below get done even
* when no requests are arriving.
* We wait at most one minute, to ensure that the other background
* tasks handled below get done even when no requests are arriving.
*/
memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set));
timeout.tv_sec = Min(60, autovacuum_naptime);
timeout.tv_sec = 60;
timeout.tv_usec = 0;
PG_SETMASK(&UnBlockSig);
@ -1238,17 +1241,13 @@ ServerLoop(void)
signal_child(BgWriterPID, SIGUSR2);
}
/*
* Start a new autovacuum process, if there isn't one running already.
* (It'll die relatively quickly.) We check that it's not started too
* frequently in autovac_start.
*/
if ((AutoVacuumingActive() || force_autovac) && AutoVacPID == 0 &&
/* If we have lost the autovacuum launcher, try to start a new one */
if ((AutoVacuumingActive() || start_autovac_launcher) && AutoVacPID == 0 &&
StartupPID == 0 && !FatalError && Shutdown == NoShutdown)
{
AutoVacPID = autovac_start();
AutoVacPID = StartAutoVacLauncher();
if (AutoVacPID != 0)
force_autovac = false; /* signal successfully processed */
start_autovac_launcher = false; /* signal successfully processed */
}
/* If we have lost the archiver, try to start a new one */
@ -1874,15 +1873,9 @@ pmdie(SIGNAL_ARGS)
ereport(LOG,
(errmsg("received smart shutdown request")));
/*
* We won't wait out an autovacuum iteration ...
*/
if (AutoVacPID != 0)
{
/* Use statement cancel to shut it down */
signal_child(AutoVacPID, SIGINT);
break; /* let reaper() handle this */
}
/* autovacuum workers are shut down immediately */
if (DLGetHead(BackendList))
SignalSomeChildren(SIGINT, true);
if (DLGetHead(BackendList))
break; /* let reaper() handle this */
@ -1904,6 +1897,9 @@ pmdie(SIGNAL_ARGS)
/* Tell pgstat to shut down too; nothing left for it to do */
if (PgStatPID != 0)
signal_child(PgStatPID, SIGQUIT);
/* Tell autovac launcher to shut down too */
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGTERM);
break;
case SIGINT:
@ -1920,15 +1916,13 @@ pmdie(SIGNAL_ARGS)
ereport(LOG,
(errmsg("received fast shutdown request")));
if (DLGetHead(BackendList) || AutoVacPID != 0)
if (DLGetHead(BackendList))
{
if (!FatalError)
{
ereport(LOG,
(errmsg("aborting any active transactions")));
SignalChildren(SIGTERM);
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGTERM);
/* reaper() does the rest */
}
break;
@ -1959,6 +1953,9 @@ pmdie(SIGNAL_ARGS)
/* Tell pgstat to shut down too; nothing left for it to do */
if (PgStatPID != 0)
signal_child(PgStatPID, SIGQUIT);
/* Tell autovac launcher to shut down too */
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGTERM);
break;
case SIGQUIT:
@ -2073,8 +2070,8 @@ reaper(SIGNAL_ARGS)
/*
* Go to shutdown mode if a shutdown request was pending.
* Otherwise, try to start the archiver and stats collector too.
* (We could, but don't, try to start autovacuum here.)
* Otherwise, try to start the archiver, stats collector and
* autovacuum launcher.
*/
if (Shutdown > NoShutdown && BgWriterPID != 0)
signal_child(BgWriterPID, SIGUSR2);
@ -2084,6 +2081,9 @@ reaper(SIGNAL_ARGS)
PgArchPID = pgarch_start();
if (PgStatPID == 0)
PgStatPID = pgstat_start();
if (AutoVacuumingActive() && AutoVacPID == 0)
AutoVacPID = StartAutoVacLauncher();
/* at this point we are really open for business */
ereport(LOG,
(errmsg("database system is ready to accept connections")));
@ -2141,18 +2141,16 @@ reaper(SIGNAL_ARGS)
}
/*
* Was it the autovacuum process? Normal or FATAL exit can be
* ignored; we'll start a new one at the next iteration of the
* postmaster's main loop, if necessary. Any other exit condition
* is treated as a crash.
* Was it the autovacuum launcher? Normal exit can be ignored; we'll
* start a new one at the next iteration of the postmaster's main loop,
* if necessary. Any other exit condition is treated as a crash.
*/
if (AutoVacPID != 0 && pid == AutoVacPID)
{
AutoVacPID = 0;
autovac_stopped();
if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus))
if (!EXIT_STATUS_0(exitstatus))
HandleChildCrash(pid, exitstatus,
_("autovacuum process"));
_("autovacuum launcher process"));
continue;
}
@ -2230,7 +2228,7 @@ reaper(SIGNAL_ARGS)
if (Shutdown > NoShutdown)
{
if (DLGetHead(BackendList) || StartupPID != 0 || AutoVacPID != 0)
if (DLGetHead(BackendList) || StartupPID != 0)
goto reaper_done;
/* Start the bgwriter if not running */
if (BgWriterPID == 0)
@ -2244,6 +2242,9 @@ reaper(SIGNAL_ARGS)
/* Tell pgstat to shut down too; nothing left for it to do */
if (PgStatPID != 0)
signal_child(PgStatPID, SIGQUIT);
/* Tell autovac launcher to shut down too */
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGTERM);
}
reaper_done:
@ -2371,7 +2372,7 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
signal_child(BgWriterPID, (SendStop ? SIGSTOP : SIGQUIT));
}
/* Take care of the autovacuum daemon too */
/* Take care of the autovacuum launcher too */
if (pid == AutoVacPID)
AutoVacPID = 0;
else if (AutoVacPID != 0 && !FatalError)
@ -2501,10 +2502,22 @@ signal_child(pid_t pid, int signal)
}
/*
* Send a signal to all backend children (but NOT special children)
* Send a signal to all backend children, including autovacuum workers (but NOT
* special children).
*/
static void
SignalChildren(int signal)
{
SignalSomeChildren(signal, false);
}
/*
* Send a signal to all backend children, including autovacuum workers (but NOT
* special children). If only_autovac is TRUE, only the autovacuum worker
* processes are signalled.
*/
static void
SignalSomeChildren(int signal, bool only_autovac)
{
Dlelem *curr;
@ -2512,6 +2525,9 @@ SignalChildren(int signal)
{
Backend *bp = (Backend *) DLE_VAL(curr);
if (only_autovac && !bp->is_autovacuum)
continue;
ereport(DEBUG4,
(errmsg_internal("sending signal %d to process %d",
signal, (int) bp->pid)));
@ -2523,6 +2539,8 @@ SignalChildren(int signal)
* BackendStartup -- start backend process
*
* returns: STATUS_ERROR if the fork failed, STATUS_OK otherwise.
*
* Note: if you change this code, also consider StartAutovacuumWorker.
*/
static int
BackendStartup(Port *port)
@ -3319,13 +3337,16 @@ SubPostmasterMain(int argc, char *argv[])
* same address the postmaster used.
*/
if (strcmp(argv[1], "--forkbackend") == 0 ||
strcmp(argv[1], "--forkautovac") == 0 ||
strcmp(argv[1], "--forkavlauncher") == 0 ||
strcmp(argv[1], "--forkavworker") == 0 ||
strcmp(argv[1], "--forkboot") == 0)
PGSharedMemoryReAttach();
/* autovacuum needs this set before calling InitProcess */
if (strcmp(argv[1], "--forkautovac") == 0)
AutovacuumIAm();
if (strcmp(argv[1], "--forkavlauncher") == 0)
AutovacuumLauncherIAm();
if (strcmp(argv[1], "--forkavworker") == 0)
AutovacuumWorkerIAm();
/*
* Start our win32 signal implementation. This has to be done after we
@ -3420,7 +3441,24 @@ SubPostmasterMain(int argc, char *argv[])
BootstrapMain(argc - 2, argv + 2);
proc_exit(0);
}
if (strcmp(argv[1], "--forkautovac") == 0)
if (strcmp(argv[1], "--forkavlauncher") == 0)
{
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
/* Restore basic shared memory pointers */
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
InitDummyProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores(false, 0);
AutoVacLauncherMain(argc - 2, argv + 2);
proc_exit(0);
}
if (strcmp(argv[1], "--forkavworker") == 0)
{
/* Close the postmaster's sockets */
ClosePostmasterPorts(false);
@ -3434,7 +3472,7 @@ SubPostmasterMain(int argc, char *argv[])
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores(false, 0);
AutoVacMain(argc - 2, argv + 2);
AutoVacWorkerMain(argc - 2, argv + 2);
proc_exit(0);
}
if (strcmp(argv[1], "--forkarch") == 0)
@ -3518,11 +3556,7 @@ sigusr1_handler(SIGNAL_ARGS)
* See storage/ipc/sinval[adt].c for the use of this.
*/
if (Shutdown <= SmartShutdown)
{
SignalChildren(SIGUSR1);
if (AutoVacPID != 0)
signal_child(AutoVacPID, SIGUSR1);
}
}
if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) &&
@ -3542,7 +3576,7 @@ sigusr1_handler(SIGNAL_ARGS)
signal_child(SysLoggerPID, SIGUSR1);
}
if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC))
if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER))
{
/*
* Start one iteration of the autovacuum daemon, even if autovacuuming
@ -3553,9 +3587,13 @@ sigusr1_handler(SIGNAL_ARGS)
* that by launching another iteration as soon as the current one
* completes.
*/
force_autovac = true;
start_autovac_launcher = true;
}
/* The autovacuum launcher wants us to start a worker process. */
if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER))
StartAutovacuumWorker();
PG_SETMASK(&UnBlockSig);
errno = save_errno;
@ -3759,6 +3797,56 @@ StartChildProcess(int xlop)
return pid;
}
/*
* StartAutovacuumWorker
* Start an autovac worker process.
*
* This function is here because it enters the resulting PID into the
* postmaster's private backends list.
*
* NB -- this code very roughly matches BackendStartup.
*/
static void
StartAutovacuumWorker(void)
{
Backend *bn;
/*
* do nothing if not in condition to run a process. This should not
* actually happen, since the signal is only supposed to be sent by
* autovacuum launcher when it's OK to do it, but test for it just in case.
*/
if (StartupPID != 0 || FatalError || Shutdown != NoShutdown)
return;
bn = (Backend *) malloc(sizeof(Backend));
if (!bn)
{
ereport(LOG,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory")));
return;
}
bn->pid = StartAutoVacWorker();
bn->is_autovacuum = true;
/* we don't need a cancel key */
if (bn->pid > 0)
{
DLAddHead(BackendList, DLNewElem(bn));
#ifdef EXEC_BACKEND
ShmemBackendArrayAdd(bn);
#endif
}
else
{
/* not much we can do */
ereport(LOG,
(errmsg("could not fork new process for autovacuum: %m")));
free(bn);
}
}
/*
* Create the opts file